Assessment of cardiovascular function by digital angiocardiography

Abstract

A methodology for computerized digital videoangiocardiography is briefly described. Single or biplane projection image series from the cardiovascular system are combined with the corresponding physiologic (electrocardiogram, blood pressure, etc.) reference data, digitized and stored as a block of simultaneously available information representing anatomic and functional aspects of the cardiovascular system. Simple mask mode and more complex modes of digital subtraction, image combination and manipulation techniques, as developed during the last decade, are mentioned. These techniques are primarily useful to separate the contrast bolus from the background, thereby allowing contrast enhancement with less contrast medium injected selectively, or so-called noninvasive intravenous angiocardiography. Ventricular function can be assessed by these simple digital image processing techniques. This has been proved for determining right ventricular volumes and ejection fraction with respect to reproducibility and accuracy using conventional biplane angiocardiography as reference. More complex techniques for the assessment of function, in particular blood flow distributions in the systemic circulation, are described using information from the whole digitized angiocardiographic image series by extracting time and volume parameters from the complete matrix of pixel densograms. Various modes of extraction and display of time parameters allow a generation of parametric images that display heretofore unavailable flow patterns reflecting the progress of the contrast bolus within the arterial tree. Based on an adequate temporal segmentation (for example, time segments of one cardiac cycle) and simultaneous volume determination of the circulatory structure from the area of the densogram, relative and absolute flow as well as regional flow distribution in a branching arterial system can be determined.(ABSTRACT TRUNCATED AT 250 WORDS)